#include <bits/stdc++.h>
using namespace std;

#define int int64_t
#define endl "\n"

using PII = pair<int, int>;
using TII = tuple<int, int, int>;
template<class T>
using V = vector<T>;
using i64 = long long;
using i128 = __int128;
using u64 = unsigned long long;

#define FOR(i, a, b) for (int i = (int)(a); i <= (int)(b); i++)
#define FOR2(i, a, b, c) for (int i = (int)(a); i <= (int)(b); i += c)
#define FORD(i, b, a) for (int i = (int)(a); i >= (int)(b); i--)
#define FORD2(i, b, a, c) for (int i = (int)(a); i >= (int)(b); i -= c)
#define ALL(a) a.begin(), a.end()
#define RALL(a) a.rbegin(), a.rend()
#define lowbit(x) ((x)&(-x))
#define RE return;
#define Yes cout << "Yes" << endl;
#define YES cout << "YES" << endl;
#define No cout << "No" << endl;
#define NO cout << "NO" << endl;
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define sz size()

void solve () {
    int n;
    cin >> n;
    V<int>w (n);
    for (auto& x : w)cin >> x;

    struct E {
        int x, y;
        bool operator<(const E& t)const {
            return y < t.y;
        }
    };

    priority_queue<E>q;
    map<int, int>mp;
    for (auto x : w)mp[x]++;

    for (auto [x, y] : mp) {
        q.push ({ x,y });
    }

    int ans = 0;

    while (q.sz >= 2) {
        E a = q.top ();
        q.pop ();
        E b = q.top ();
        q.pop ();

        if (a.y > 1) {
            q.push ({ a.x,a.y - 1 });
        }
        if (b.y > 1) {
            q.push ({ b.x,b.y - 1 });
        }
    }

    while (q.sz) {
        ans += q.top ().y;
        q.pop ();
    }

    cout << ans << endl;

}

signed main () {
    int Task = 1;

    ios::sync_with_stdio (false);
    cin.tie (nullptr);
    cin >> Task;

    while (Task--) {
        solve ();
    }

    return 0;
}